<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>第一题</title>
    <style>
        .box1:hover{
            width: 200px;
			height: 200px;
			background-color: brown;
        }
    </style>
</head>
<body>
    <div id="app">
        <div :class="c1">
            1. 鼠标放上去显示 移开消失
        </div>
    </div>
</body>
<script src="./vue.js"></script>
<script>
    const{ createApp,ref}=Vue
    createApp({
        setup(){
            let c1 = ref('box1')
            return{
                c1 
            }
        }
        

    }).mount('#app')
</script>
</html>